去掉重复项distinct和以指定顺序排序order by 出现错误

[hhm1016]

SQL语句：
select distinct mc from tkh
order by
(select CASE mc WHEN '董事长' THEN 1 WHEN '副董' THEN 2 WHEN '经理' THEN 3 WHEN '副经理' THEN 4 end)


错误提示：如果指定了 SELECT DISTINCT，那么 ORDER BY 子句中的项就必须出现在选择列表中。

说明:我查询出来的有重复项，我想先去掉重复项，然后在按以指定的顺序排列，请问该怎么修改呢？？？
高手请解答，谢谢。。。

[水族杰纶]

select distinct mc from tkh
order by  
(CASE mc WHEN '董事长' THEN 1 WHEN '副董' THEN 2 WHEN '经理' THEN 3 WHEN '副经理' THEN 4 end) 

[SQLCenter]

select * from
(select distinct mc from tkh) t
order by (select CASE mc WHEN '董事长' THEN 1 WHEN '副董' THEN 2 WHEN '经理' THEN 3 WHEN '副经理' THEN 4 end) 

[水族杰纶]

--更正
select  mc 
from tkh
group by mc
order by  
(CASE mc WHEN '董事长' THEN 1 WHEN '副董' THEN 2 WHEN '经理' THEN 3 WHEN '副经理' THEN 4 end) 

[Rotel-刘志东]

select  mc 
from tkh
group by mc
order by  
(CASE mc WHEN '董事长' THEN 1 WHEN '副董' THEN 2 WHEN '经理' THEN 3 WHEN '副经理' THEN 4 end) 

[Mr_Nice]

SELECT  *
FROM    ( SELECT DISTINCT
                    mc
          FROM      tkh
        ) T
ORDER BY ( CASE mc
             WHEN '董事长' THEN 1
             WHEN '副董' THEN 2
             WHEN '经理' THEN 3
             WHEN '副经理' THEN 4
           END )  

???
最好来点儿数据和结果。

[--小F--]

ORDER BY CASE...WHEN

[hhm1016]

[Quote=引用 5 楼 orchidcat 的回复:]
SQL code
SELECT *
FROM ( SELECT DISTINCT
mc
FROM tkh
) T
ORDER BY ( CASE mc
WHEN '董事长' THEN 1
WHEN '副董' THEN 2
……
[/Quote]

谢了，我再问下，就是有多个左连接的话该怎么写了？？
比如：
select distinct tb1.num,tb2.name,tb2.age,tb3.mc
from tb1
left join tb2 on tb1.num=tb2.num
left join tb3 on tb1.num=tb3.num
order by (
CASE mc
WHEN '董事长' THEN 1
WHEN '副董' THEN 2
……

)